Antonyms of adj sportive

1 of 2 senses of sportive

Sense 2
coltish, frolicsome, frolicky, rollicking, sportive -- (given to merry frolicking; "frolicsome students celebrated their graduation with parties and practical jokes")

INDIRECT (VIA playful) -> unplayful, serious, sober -- (completely lacking in playfulness)

Similarity of adj sportive

2 senses of sportive

Sense 1
sportive -- (relating to or interested in sports)

Sense 2
coltish, frolicsome, frolicky, rollicking, sportive -- (given to merry frolicking; "frolicsome students celebrated their graduation with parties and practical jokes")
       => playful (vs. unplayful) -- (full of fun and high spirits; "playful children just let loose from school")